PAR3は,トロンビンによる PAR4活性化のコファクターである.
M Nakanishi-Matsui1, Y W Zheng, D J Sulciner
1Cardiovascular Research Institute and Daiichi Research Center, University of California, San Francisco 94143-0130, USA.
Nature
|April 15, 2000
まとめ
トロンビンは,プロテアゼ活性化受容体 (PAR) を介して血小板を活性化します. マウスのPAR3はコファクタとして作用し,トロンビンがPAR4を活性化させ,Gタンパク質結合受容体シグナル伝達のための新しいメカニズムを明らかにします.
科学分野:
- バイオケミストリー バイオケミストリー
- 細胞生物学 細胞生物学
- 血液学 ヘマトロジ
背景:
- 重要な凝固プロテアゼであるトロンビンは,プロテアゼ活性化Gタンパク質結合受容体 (PARs) を介して血小板を活性化します.
- PAR3とPAR4は,マウスの血小板に存在するトロンビン受容体であり,PAR3はトロンビンの低濃度において極めて重要です.
- 以前の研究では,ヒトの PAR3 がトロンビンに反応することを示しましたが,マウス PAR3 (mPAR3) は,その重要性にもかかわらず,直接信号を与えませんでした.
研究 の 目的:
- マウスにおけるPAR3およびPAR4を含む,トロンビン誘発の血小板活性化のメカニズムを解明する.
- マウス PAR3とマウス PAR4の機能的相互作用を調査する.
- コファクター支援のGタンパク質結合受容体活性化のための新しいパラダイムを確立する.
主な方法:
- マウスの血小板におけるトロンビン受容体の機能を研究した.
- 遺伝子ノックアウトと異質発現システムを活用した.
- mPAR3とmPAR4.4の相互作用を分析した.
主要な成果:
- マウスPAR3 (mPAR3) は,直接的にトロンビンシグナリングを媒介するものではありません.
- mPAR3はコファクターとして機能し,トロンビンの分裂とmPAR4の活性化を促進します.
- この相互作用は,トロンビン誘発による血小板活性化に不可欠である.
結論:
- マウスPAR3は補助分子として作用し,PAR4にトロンビンを提示します.
- このコファクタアシストメカニズムは,Gタンパク質結合受容体の活性化のための新しい経路を表しています.
- この相互作用を理解することは,血液静止症と血栓症の研究にとって非常に重要です.
関連する概念動画
Cofactors and Coenzymes
87.7K
Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.
87.7K
Cofactors and Coenzymes
12.8K
Enzymes are proteins made of amino acids. The functional group of each constituent amino acid catalyzes a wide variety of chemical reactions via ionic interactions or acid-base reactions. However, amino acids cannot catalyze oxidation-reduction and group transfer reactions and need to be aided by non-protein components called cofactors. Cofactors are also referred to as the chemical teeth of an enzyme.
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
12.8K
Co-activators and Co-repressors
8.7K
Gene transcription is regulated by the synergistic action of several proteins that form a complex at a gene regulatory site. This is observed in eukaryotes, where the regulation of gene expression is a complex process. Regulatory proteins in eukaryotes can broadly be classified into two types – regulators that bind directly to specific DNA sequences and co-regulators that associate with regulatory proteins but cannot directly bind to the DNA. These co-regulators are further divided into...
8.7K
tRNA Activation
23.1K
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
23.1K
Activation Energy
87.1K
Activation energy is the minimum amount of energy necessary for a chemical reaction to move forward. The higher the activation energy, the slower the rate of the reaction. However, adding heat to the reaction will increase the rate, since it causes molecules to move faster and increase the likelihood that molecules will collide. The collision and breaking of bonds represents the uphill phase of a reaction and generates the transition state. The transition state is an unstable high-energy state...
87.1K
Eukaryotic Transcription Activators
12.9K
Transcription activators are proteins that promote the transcription of genes from DNA to RNA. In most cases, these proteins contain two separate domains ‒ a domain that binds to DNA and a domain for activating transcription; however, in some cases, a single domain is responsible for both binding and activation of transcription, as seen in the glucocorticoid receptor and MyoD.
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These...
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These...
12.9K


